1. Field of the Invention
The present invention is related to a network data transfer system, and more particularly, to an asymmetric Ethernet network data transfer system.
2. Description of the Prior Art
With the quick improvements in technology, the network has become an indispensable communication medium in modern society. Of all the networks, the local area network is the most popular one due to the well-developed and inexpensive devices of it. The Ethernet is a common local-area-network technique. It consists of an Ethernet card and other network connection devices. The conventional Ethernet has a symmetry feature in data transfer, which means that the bandwidths used in the downloading and uploading data transfer works are equal. However, usually the practical downloading and the practical uploading data transfer rates are different. Thus, the symmetry feature often causes congestion problems to data transfer in the transfer direction with insufficient bandwidth and leaves bandwidth unused in the transfer direction with transfer bandwidth more than needed.
Reference is now made to FIG. 1, which is a block diagram illustrating a conventional Ethernet network interface card 100. The conventional Ethernet network interface card 100 comprises: a negotiating module 110 to negotiate with the target network apparatus for the packet format for data transfer; for example, the IP (internet protocol) packet format a transforming module 120 to perform the transformation between the digital data (such as the computer terminal) and the packets (such as the network terminal) according to the packet format agreed on; and a transmitting/receiving module 130 which further comprises a transmitting agent 130A and a receiving agent 130B. Take the transmitting agent 130A for example, the main mission of it is to send out the packets from the transforming module 120. The network cable connected to the transmitting agent 130A and the receiving agent 130B are both in one-way transfer mode, i.e. the packets in the network cable connected to the transmitting agent 130A all travel towards a target network apparatus 140A (another apparatus with a network interface card); and the packets in the network cable connected to the receiving agent 130B all travel towards the network interface card 100 itself (or say the packets all travel towards the slot 140B in which the network interface card 100 is set and then into the CPU). Since the physical bandwidth of each network cable is of the same size, in the above case the network interface card 100 practically utilizes the same bandwidth for both the downloading and uploading data transfer works, which is what called the symmetry feature of the Ethernet. However, in real cases the downloading data transfer rate and the uploading data transfer rate usually are not the same. For example, general network end users download more than upload. Thus, while transferring data, the symmetry feature of the Ethernet often causes congestion problems to the data transfer in the transfer direction with insufficient bandwidth and leaves bandwidth unused in the transfer direction with transfer bandwidth more than needed. To solve this problem, the present invention provides an asymmetric Ethernet network data transfer system which can allocate the bandwidth in a more proper manner.